Summary

Description

A short thallus with a stout midrib arises from a discoid holdfast, widening as it branches into flattened red-brown or red-purple fronds to a height of 20 cm. The fronds are thin and membranous, around 2.5 cm in width and may have a slight blue iridescence under water. Repeated branching gives it a bushy tangled appearance with the branches tapering to rounded tips. Morphology is variable and blades can be either erect or prostrate and broadly-wedged or strap-shaped. Margins may be smooth, undulating, denticulate or hooked.
frequently with a blue iridescence underwater.

Recorded distribution in Britain and Ireland

Distributed around Britain and Ireland, being recorded more commonly in the south and sparsely in the east.

Global distribution

Found from southern Norway and the Faeroe Isles to Spain. Also recorded in the Mediterranean and Brazil.

Habitat

Found subtidally growing on rock and Laminaria hyperborea stipes.
Grows on shaded areas on the sides of deep pools or under the cover of Fucus species in the intertidal.

The erect blades are attached with a stipe-like structure resulting from basal erosion of the lamina exposing the midrib.

The midrib divides with the branches but becomes indistinct in the upper regions.

The veins are approximately parallel and visible under bright light.

Cystocarps are strewn all over the thallus and the tetrasporangia occur in broken lines along the margin or lateral proliferations.

The male is distinguishable from the female as it is smaller and has pale antheridial patches near the tips of its branches.

Additional information

Cryptopleura ramosa var. uncinata has characteristic hooked margins. The marginal hooks distinguish it from the similar Acrosorium venulosum that has both terminal and marginal hooks. When fan-shaped, Cryptopleura ramosa may closely resemble Erythroglossum laciniatum but may be distinguished by the margins and venation. Polyneura bonnemaisonii, another similar species, differs from Cryptopleaura ramosa in the more scattered distribution of the tetrasporangia and spiny outer wall to the cystocarps. Polyneura bonnemaisonii infrequently displays prostate blades, and the haptera attaching them to the substrate, are marginal as opposed to the peg-like haptera seen in Cryptopleura ramosa.

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